Plastic container and lid therefor



y 1970 F. E. ULLMAN ETAL 3,510,023

PLASTIC CONTAINER AND LID THEREFOR 2 Sheets-Sheet 1 Filed Aug. 14, 1968 WRIWHSHA 3 INV ENTORS FREDERICK E, ULLMAN MINDAUGAS Juuus Kwaas y 1970 F. E. ULLMAN ETAL 3,510,023

PLASTIC CONTAINER AND LID THEREFOR Filed Aug. 14, 1968 2 Sheets-sneer 2 Wily/[Z 10 INVENT RS FREDERICK E. ULLMAN MINDAUGAS Juuus kurels 2- 4, 116%,, M01, vmwim Arrvs.

United States Patent M 3,510,023 PLASTIC CONTAINER AND LID THEREFOR Frederick E. Ullman, Winnetka, and Mindaugas J. Klygis,

Evergreen Park, 111., assignors to Inland Steel Company, Chicago, 111., a corporation of Delaware Filed Aug. 14, 1968, Ser. No. 752,556 Int. Cl. B65d 93/10 US. Cl. 220-60 18 Claims ABSTRACT OF THE DISCLOSURE A plastic container and lid, each of unitary construction and formed at least in part of self-supporting plastic material. The sidewall of the container forms at least one circumferential rib on the outer surface thereof adjacent the upper end, and the lid includes a depending peripheral skirt the inner surface of which has a portion complementary to the rib on the container for locking the lid and container together. The lid may be snapped down over the container rib, or it may be threaded into engagement therewith. A laterally projecting tab may be provided on the lid to facilitate removal. The container bottom and the lid are dimensioned to permit stacking with secure nesting of the bottom of one container in the lid of another.

The present invention relates generally to containers and, more particularly, to open-head containers with removable lids, of the type commonly used in transporting and/ or storing liquid, semi-liquid, pulverized, granular or other substances.

The development of self-supporting plastic shipping containers has given rise to the problem of affixing a removable plastic lid to an open-head plastic container in a manner which will maintain the liquid-tight integrity of the container when subjected to the usual hazards of shipping and handling filled containers. This is a problem not only with liquids, but also with semi-liquid of finely pulverized or granular materials. A number of solutions to this problem have been proposed heretofore, but they have not yet been completely satisfactory, as evidenced by the fact that a number of plastic containers are still fitted with steel covers using methods similar to those used in affixing steel covers to steel containers.

It is, therefore, a primary object of the present invention to provide an improved plastic container and lid construction that permits both the container and the lid to be made at least in part of self-supporting plastic material, while providing a sealing and locking arrangement between the container and lid which maintains the liquidtight integrity of the container even when subjected to rigorous shipping, storage and handling conditions.

It is another object of the present invention to provide such an improved plastic container and lid construction which permits the lid to be applied to and removed from the container with great facility.

A further object of the invention is to provide an improved plastic container and lid construction of the type described above which can be economically manufactured at high production rates.

It is an object of one particular aspect of this invention to provide such an improved plastic container and lid construction which facilitates stacking of the filled containers, while providing good drainage from the container lids.

Other objects and advantages of the invention will become apparent from the following detailed description taken .in conjunction with the accompanying drawings, in which:

FIG. 1 is a top plan view of a plastic container and lid 3,510,023 Patented May 5, 1970 embodying the present invention, with a portion of the lid broken away to show the underlying container structure;

FIG. 2 is a side elevation, partially in section, of the lid shown in FIG. 1, removed from the container;

FIG. 3 is a side elevation, partially in section, of the container shown in FIG. 1, with the lid removed;

FIG. 4 is an enlarged fragmentary section of the peripheral portion of the lid shown in section in FIG. 2;

FIG. 5 is an enlarged fragmentary section of the top portion of the container wall shown in section in FIG. 3, with a portion of the lid of FIG. 4 being shown in broken lines to illustrate its position during application thereof;

FIG. 6 is an enlarged fragmentary section of the two elements shown in FIGS. 4 and 5 in their assembled positions;

FIG. 7 is a side elevation, partially in section, of a modified lid adapted for use with the container of FIG. 2;

FIG. 8 is a fragmentary plan view of another modified lid structure;

FIG. 9 is a section taken along line 9-9 in FIG. 8;

FIG. 10 is an enlarged fragmentary section similar to FIG. 6, but showing a further modified container and lid construction embodying the present invention;

FIG. 11 is a top plan view of still another modified plastic container and lid embodying the present invention, with a portion of the lid broken away to show the underlying structure, and illustrating a fastening and removal tool for use with the modified lid;

FIG. 12 is a side elevation, partially in section of the lid shown in FIG. 11, removed from the container;

FIG. 13 is a side elevation, partially in section of the container shown in FIG. 11, with the lid removed;

FIG. 14 is an enlarged fragmentary section of the peripheral portion of the lid shown in FIG. 12;

FIG. 15 is an enlarged fragmentary section of the top portion of the container wall shown in section in FIG. 13; and

FIG. 16 is an enlarged fragmentary section of the two elements shown in FIGS. 14 and 15 in their assembled positions.

While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

Referring now to the drawings, there is shown in FIGS. 1 through 6 an open-head container 10 of unitary construction and formed of self-supporting plastic material. More particularly, the container includes a bottom wall 11 and an integral sidewall 12 extending upwardly therefrom. The particular plastic material from which the container 10 is made is not critical to the present invention, it being understood that the container will be formed of material that is inert with respect to the substances to be stored therein. In the particular embodiment illustrated, a pair of axially spaced reinforcing members 13 are formed as integral parts of the container sidewall 12, and extend continuously around the circumference thereof. As in the case of the plastic material, the particular configuration of the bottom wall 11 and the main body portion of the sidewall 12 is not critical to the present invention, and may take a variety of different forms.

In accordance with one of the important aspects of the present invention, the container sidewall forms at least one circumferential rib on the outer surface thereof adjacent its upper end, and a lid of unitary construction and formed of self-supporting plastic material is removably affixed to the upper end of the container sidewall via a peripheral skirt extending downwardly past the lower edge of the rib on the container sidewall with the inner surface of the skirt having a portion complementary to the rib so as to mesh therewith. Thus, in the illustrative embodiment, the sidewall 12 of the plastic container forms a pair of integral circumferential ribs and 21, the upper rib 20 being located on the upper edge of the sidewall and the lower rib 21 being axially spaced a small distance below the upper rib 20 and parallel thereto. The ribs 20, 21 cooperate with a lid 30, to be described in more detail below, to provide a liquid-tight, dust-tight closure which is maintained throughout the usual hazards involved in the shipping and handling of such containers.

Referring particularly to FIGS. 1, 2, 4, and 6, the lid is of unitary construction and is formed of self-sup porting plastic material. As in the case of the container 10, the particular material selected is not critical to the present invention, it being understood that it will be inert with respect to the substances to be stored in the container. To permit both the loading of substances into the container 10 and their subsequent complete or partial removal therefrom, the lid 30 is both removable and re placeable and, as will be apparent from the ensuing discussion, the structural features provided by this invention enable the removal and replacement operations to be accomplished with great facility. In the assembled position, as best illustrated in FIG. 6, a skirt 31 on the periphery of the lid extends downwardly past the lower edge of the lower rib 21 on the container sidewall 12, with the inner surface of the skirt 31 having a portion complementary to the ribs 20, 21 so as to mesh therewith. More particularly, the inner surface of the skirt 31 forms a first integral circumferential rib 32 designed to fit between the ribs 20 and 21 on the container sidewall, and a second integral circumferential rib 33 designed to fit directly beneath the lower rib 21 in bearing engagement therewith. The engaging surfaces of the cooperating ribs 20, 21 and .32, 33, respectively, are preferably tapered as illustrated so that the ribs are effectively wedged between each other as the skirt and the container sidewall are drawn together by means to be described below.

As the lid 30 is positioned on top of the container 10 and pushed downwardly thereon, a beveled edge 34 on the lower end of the depending skirt 31 engages the rib and cams the resilient skirt 31 outwardly as illustrated in broken lines in FIG. 5. Since relatively little pressure is required to effect this camming action, the lid 30 can be applied to the container 10 quickly and easily. When the lid has been advanced far enough to align the ribs 21, 22 with the complementary portion of the skirt 31, the skirt snaps back to its normal vertical position with the ribs 32, 33 meshing with the container ribs 20, 21 as illustrated in FIG. 6, thereby locking the lid to the container while also serving as a seal between the container contents and the external environment. In addition to its camming function, the beveled edge 34 provides a grip which can be used to pry the skirt 31 away from the container sidewall 12 to disengage the interlocking ribs 20, 21 and 32, 33.

In keeping with the invention, the unitary plastic lid 30 also forms a circumferentially disposed annular portion 35 which extends from the top of the skirt 31 downwardly along the inner surface of the container sidewall 12 at least as far as the lower edge of the rib 21 on the outer surface of the sidewall. Thus, the annular portion 35 backs up the entire upper portion of the container sidewall 12 on the inner surface thereof opposite the interlocking ribs 20, 21 and 32, 3.3 to prevent the ribs from becoming disengaged due to deflection of the upper portion of the sidewall 12 away from the depending skirt 31, for example. In the particular embodiment illustrated, the annular portion 35 merges with a fiat central wall 36 which covers the open end of the container 10 at the same level as the lower end of the annular portion 35, thereby hold ing the annular portion 35 closely adjacent the inner sur* face of the container wall 12 to provide a relatively rigid and tight container-lid assembly.

To further improve the strength and rigidity of the lid 31, an integral annulus 37 is spaced inwardly from the annular portion 35 and extending upwardly from the depressed central wall 36, and a plurality of radial ribs 38 interconnect the annulus 37 with the annular portion 35. Since the annulus 37 extends continuously around the entire circumference of the lid 30, and the radial ribs 38 are spaced at regular intervals around the entire circumference, it can be seen that the annular region of the lid 30 adjacent the inner surface of the container wall 12 forms a radially stifl? structure to provide firm support for the upper portion of the container sidewall on which the sealing and locking ribs 20, 21 are formed. Consequently, the ribs 20, 21 are maintained in tight engagement with the complementary portion of the depending skirt 31 even in the face of sudden impacts such as are encountered during normal shipping and handling of such containers. If desired, the top portion of the skirt 31 may be made thin enough to permit that portion of the skirt to be stretched slightly as the lid is pushed onto the container.

In order to accommodate a sealing gasket between the lid .30 and the container 10 to further enhance the liquidtight and dust-tight integrity of the container, the top rim 3) of the lid is dimensioned to form a narrow cavity 39 between the inner surface thereof and the top edge of the container sidewall when the lid is aliixed to the container. This cavity receives a gasket 40 which is engaged by a relatively sharp upper edge 41 formed by internal and external bevels on the top edge of the sidewall 12 to insure intimate engagement and deformation of the gasket 40, as illustrated in FIG. 6. Moreover, since the gasket 40 is disposed above the ribs 32 and 33, it is retained within the cavity 39 by the ribs 32, 33 and the opposed annular portion 35 so that it cannot drop out during handling of the lid. The gasket 40 may be a flow-in curedin-place gasket or a sponge rubber or hollow tubular gasket preassembled into the gasket cavity formed beneath the rim 39 of the lid 30.

If desired, the outside surface of the depending skirt 31 may be slightly indented to form a shallow groove 42 for receiving a tensioning and reinforcing ring or strap 43, as shown in FIG. 6. As the strap 43 is drawn tightly around the circumference of the lid 30 after it has been afiixed to the container 10, it draws the depending skirt 31 and the upper portion of the container sidewall 12 into tight engagement with each other and against the relatively rigid back-up annulus provided by the annular portions 35 and 37 and the interconnecting ribs 38 adjacent the inner surface of the sidewall 12. The strap 43 may be made of metal or suitable plastic or other materials, and may be fastened by methods which are conventionally used for such strapping in the container art. When a tensioning reinforcing strap 43 is used in conjunction with the present invention, the lid 30 may be modified as illustrated in FIG. 7 (in which portions identical to the lid of FIGS. 16 have been represented by identical reference numbers), i.e., by forming a series of vertical slits 44 in the lid skirt so as to provide a discontinuous skirt made up of a series of arcuate segments 45; this construction renders the skirt more flexible than the continuous skirt illustrated in FIGS. 1 through 6, thereby facilitating application of the lid to the container and also permitting the skirt to be drawn into tighter sealing engagement with the container ribs 20, 21 during application of the tensioning strap 43.

A further advantage of the lid configuration of FIGS. 1 through 6 is that it permits a plurality of containers to be securely nested when stacked one on top of the other With the lids in place. As best illustrated in FIG. 3, the container 10 is tapered so that the diameter at the bottom of the sidewall 12 is greater than the diameter at the top. To permit the stacking of such a container on the lid of another container, the diameters can be dimensioned so that the diameter at the bottom of the container is just slightly smaller than the inside diameter of the lid 30 at the inner surface of the annular portion 35, so that the bottom of the container will fit down inside the rim 39 and rest on the vertical annulus 37 and the radial ribs 38. Alternatively, to provide an even more secure nesting effect, the container may be dimensioned to have a bottom diameter slightly smaller than the inside diameter of the lid 30 at the inner surface of the annulus 37, so that the container will fit down inside the annulus 37, and rest on the generally flat central wall portion 36. If a container having a straight vertical side is desired, a slight offset may be formed at the bottom of the container to provide the same bottom diameters described above.

Another possible modification is shown in FIGS. 8 and 9 (in which portions identical to portions shown in FIGS. 1-6 have been represented by identical reference numerals), in which the lid 30 includes a laterally extending tab 50 to facilitate removal of the lid 30 from the container 10. In the particular embodiment illustrated, a pair of ribs 51 and 52 are formed on both the top and bottom surfaces of the tab 50 near the outer end thereof to facilitate gripping of the tabs. When the outer end of the tab 50 is pulled upwardly, it can be seen that it will not only tend to lift the lid 30 upwardly off the container, but will also tend to pull the skirt 31 away from the container sidewall 12, thereby disengaging the ribs 32, 33 on the skirt from the complementary ribs 20, 21 on the container.

In a further modification, illustrated in FIG. 10 (in which portions identical to portions shown in FIGS. 1-6 have been represented by identical reference numbers) both the upper portion of the container sidewall 12 and the corresponding annular portion 35 of the lid 30 are formed at a slight angle so that the surfaces 60, 61 will firmly engage each other when the lid is applied to the container, thereby providing a further sealing area. Although the gasket 40 has been retained in this modified construction as shown in FIG. 10, the additional sealing efiect provided by the intimate contact between surfaces 60 and 61 may be sufiicient to permit the gasket to be eliminated in certain applications, depending upon the nature of the particular substance placed in the container.

Still another modified embodiment of the invention is illustrated in FIGS. 11 through 16, in which elements which are similar (not necessarily identical) to elements previously described have been identified by the same reference numerals with the addition of the distinguishing suffix a. In this particular embodiment, the sealing and locking ribs 20a and 21a on the container sidewall 12a comprise a single continuous helical rib which forms a threaded surface for cooperation with a complementary portion of the inner surface of skirt 31a. More particularly, the skirt 31a includes a pair of ribs 32a, 33a which comprise different portions of a single continuous helical rib to form the desired threaded connections. In order to apply the lid 30a to the container 10a, it is simply threaded downwardly thereover until the upper edge 41a of the container sidewall abuts the inside surface of the lid, as illustrated in FIG. 16. To facilitate the application of the lid, as well as the removal thereof, a series of diametrically opposed upstanding lugs 70 are formed on the top of the lid so that a rigid bar or other tool 71 may be inserted therebetween, as illustrated in FIG. 11, and turned clockwise or counterclockwise to turn the lid onto or off, respectively, the container 10a. To provide a tight seal between the lid and the container, a circumferential groove 72 is formed in the lower surface of the lid directly over the beveled upper edge of the container sidewall so the relatively sharp upper edge of the container is wedged into the groove 72 when the lid is threaded onto the container.

In accordance with another aspect of this particular embodiment of the invention illustrated in FIGS. 11 through 16, the annular portions 35a and 37a, as well as the interconnecting ribs 38a, are formed on the under side of the central wall 36a of the lid. This provides a greater available volume inside the container, and yet a relatively rigid structure is still provided directly adacent the inside surface of the top portion of the container wall 12a. Moreover, the lugs 70 may be dimensioned to permit the stacking of two or more containers, i.e., with the bottom of one container resting inside the lugs 70 on the lid of another container. This construction also permits good drainage from the top of the lid 30a, due to the intermittent or discontinuous nature of the series of lugs 70.

While the invention has been described with particular reference to certain specific embodiments which have been described in some detail, further modifications and alternatives will be apparent to those skilled in the art from the foregoing description. For example, the interlocking ribs on both the lid and the container could be made discontinuous with the spaces between the rib segments on the container being wide enough to pass the rib segments on the lid without deflecting the lid skirt. Thus, the lid and the container could be assembled by pushing the lid downwardly until the ribs thereon were positioned between the ribs of the container, and then twisting the lid to align the ribs of the lid and container with each other and thereby lock the lid in place. This modification can be employed with either the straight circumferential ribs of FIGS. 1 through 10, or the helical thread-forming ribs of FIGS. 11 through 16.

As can be seen from the foregoing detailed description, this invention provides an improved plastic container and lid construction that permits both the container and the lid to be made entirely of self-supporting plastic material, and with each having a unitary construction which can be economically formed in a single molding operation, for example. The sealing and locking arrangement provided by the invention maintain the liquid-tight and dust-tight integrity of the container even when subjected to rigorous shipping, storage and handling conditions, such as sudden impacts and the like. Moreover, the lid can be applied to and removed from the container with great facility, and is replaceable so that the contents of the contanier can be enclosed between withdrawals. Furthermore, certain embodiments of the invention described herein greatly facilitate stacking of the filled containers with secure nesting, while providing good drainage from the container lids.

We claim as our invention:

1. A plastic container comprising the combination of a container of unitary construction and formed of selfsupporting plastic material, said container having a bottom wall and an integral sidewall extending upwardly therefrom, said sidewall forming at least one circumferential rib on the outer surface thereof, and a lid of unitary construction and formed of self-supporting plastic material, said lid being removably affixed to the upper end of said sidewall via a resilent peripheral skirt extending downwardly past the lower edge of said rib on the container sidewall with the inner surface of said skirt having a portion complementary to said rib so as to mesh therewith, the lower portion of said skirt and said rib being adapted to cooperate with each other to deflect said skirt away from said rib as said lid is advanced downwardly over said sidewall until said complementary portion of said skirt is aligned with said rib whereupon said skirt returns to its normal position in meshing engagement with said rib, the central portion of said lid forming a laterally rigid supporting surface closely adjacent the inner surface of said sidewall opposite said skirt on the outer surface thereof to prevent flexing movement of said sidewall inwardly away from said skirt.

7 2. A container as set forth in claim 1 wherein said central portion of said lid includes an integral circumferentially disposed annular portion extending from the .top of said sidewall downwardly along and closely adjacent to the inner surface thereof at least as far as the level of said rib on the outer surface of said sidewall.

3. A container as set forth in claim 2 wherein said annular portion and the adjacent portion of the inner surface of said sidewall are both tapered inwardly from the top edge of said sidewall.

4. A plastic container comprising the combination of a container of unitary construction and formed of a self-supporting plastic material, said container having a bottom wall and an integral sidewall extending upwardly therefrom, said sidewall forming at least one circumferential rib on the outer surface thereof adjacent the upper end thereof; a lid of unitary construction and formed of self-supporting plastic material, said lid being removably aflixed to the upper end of said sidewall via a resilient peripheral skirt extending downwardly past the lower edge of said rib on the container sidewall with the inner surface of said skirt having a portion complementary to said rib so as to mesh therewith, the lower portion of said skirt and said rib being adapted to cooperate with each other to deflect said skirt away from said rib as said lid is advanced downwardly over said sidewall until said complementary portion of said skirt is aligned with said rib whereupon said skirt returns to its normal position in meshing engagement with said rib, the central portion of said lid forming a laterally rigid supporting surface closely adjacent the inner surface of said sidewall opposite said skirt on the outer surface thereof to prevent flexing movement of said sidewall inwardly away from said skirt, said skirt forming a groove extending circumferentially around the outer surface thereof; and a clamping ring disposed within said groove and extending circumferentially around said lid to clamp said lid in place upon said container.

5. A container as set forth in claim 1 wherein the entire central portion of said lid within said sidewall is disposed 'below the upper edge of said sidewall when said lid is aflixed to said container, with an annular portion of said lid interconnecting said skirt and said central portion extending along and closely adjacent to the inner surface of said sidewall.

6. A plastic container comprising the combination of a container of unitary construction and formed of selfsupporting plastic material, said container having a bottom wall and an integral sidewall extending upwardly therefrom, said sidawall forming at least one circumferential rib on the outer surface thereof adjacent the upper end thereof, and a lid of unitary construction and formed of self-supporting plastic material, said lid being removably aflixed to the upper end of said sidewall via a resilient peripheral skirt extending downwardly past the lower edge of said rib on the container sidewall with the inner surface of said skirt having a portion cornplementary to said rib so as to mesh therewith, the lower portion of said skirt and said rib being adapted to cooperate with each other to deflect said skirt away from said rib as said lid is advanced downwardly over said sidewall until said complementary portion of said skirt is aligned with said rib whereupon said skirt returns to its normal position in meshing engagement with said rib, the entire central portion of said lid within said sidewall being disposed below the upper edge of said sidewall, with an annular portion of said lid interconnecting said skirt and said central portion extending along and closely adjacent to the inner surface of said sidewall, said lid including an integral annulus spaced inwardl from said annular interconnecting portion and extending upwardly from said central portion, and a plurality of radial ribs interconnecting said annulus and said annular interconnecting portion.

7. A plastic container comprising the combination of a container of unitary construction and formed of selfsupporting plastic material, said container having a bottom wall and an integral sidewall extending upwardly therefrom, said sidewall forming a first integral rib on the upper periphery thereof and a second integral rib spaced below said first rib, and a lid of unitary construction and formed of self-supporting plastic material, said lid being removably aflixed to the upper end of said sidewall via a resilient peripheral skirt extending downwardly past the lower edgeof said second integral rib on the container sidewall, said skirt forming a first integral rib adapted to fit between the first and second ribs on said sidewall, and a second integral rib adapted to fit directly beneath said second rib on said sidewall, the lower portion of said skirt and said ribs on said sidewall being adapted to cooperate with each other to deflect said skirt away from said sidewall ribs as said lid is advanced downwardly over said sidewall until said complementary portions of said skirt are aligned with said sidewall ribs whereupon said skirt returns to its normal position in meshing engagement with said sidewall ribs.

8. A container as set forth in claim 7 wherein the cooperating surfaces of said ribs are all complementally tapered so that said surfaces are drawn into tighter engagement with each other in response to movement of said skirt and said sidewall relatively toward each other.

9. A container as set forth in claim 1 wherein said lid includes an integral tab projecting laterally from said skirt to facilitate removal of said lid from said container.

10. A container as set forth in claim 1 wherein said lid includes a sealing gasket disposed on the lower surface of the lid adjacent the upper end of said peripheral skirt for engagement with the upper edge of the container sidewall, said upper edge being beveled to form a relatively sharp edge for intimate engagement with and deformation of said gasket to provide a tight seal between said lid and said container.

11. A container as set forth in claim 2 wherein said lid includes a sealing gasket disposed on the lower surface of said lid above said complementary portion of said skirt so that the gasket is retained in the upper portion of the cavity between said skirt and said annular portion of said lid for engagement with the upper end of the container sidewall.

12. A plastic container comprising the combination of a container of unitary construction and formed of self-supporting plastic material, said container having a bottom wall and an integral sidewall extending upwardly therefrom, said sidewall forming at least one circumferential rib on the outer surface thereof adjacent the upper end thereof, and a lid of unitary construction and formed of selfsupporting plastic material, said lid being removably af fixed to the upper end of said sidewall via a resilient peripheral skirt extending downwardly past the lower edge of said rib on the container sidewall with the inner surface of said skirt having a portion complementary to said rib so as to mesh therewith, said lid also forming a circumferentially disposed annular portion extending from the top of said sidewall downwardly along and closely adjacent to the inner surface thereof at least as far as the level of said rib on the outer surface of said sidewall, the central portion of said lid forming a laterally rigid support for said annular portion to prevent flexing movement of said sidewall inwardly away from said skirt.

13. A plastic container as set forth in claim 12 wherein said rib on the container sidewall forms a threaded surface for cooperation with a complementally threaded surface on said skirt.

14. A plastic container as set forth in claim 13 wherein said lid also forms at least one pair of diametrically opposed lugs extending upwardly from said lid above the upper edge of said sidewall.

15. A container as set forth in claim 13 wherein said lid also forms a circumferential groove in the lower surface thereof between said peripheral skirt and said annular portion, and the upper edge of the container sidewall is beveled to form a relatively sharp edge adapted to register with said groove when the lid is threaded onto the container to provide a tight seal between said lid and said container.

16. A plastic container as set forth in claim 12 wherein said lid also forms a circumferentially disposed annulus spaced radially inwardly from said annular portion and extending downwardly from said lid within said container to reinforce the central portion of said lid.

17. A plastic container comprising the combination of a container of unitary construction and formed of selfsupporting plastic material, said container having a bottom wall and an integral sidewall extending upwardly therefrom, and a lid of unitary construction and formed of selfsupporting plastic material, said lid forming a sealing surface in sealing engagement with the top edge of said container side-wall, said container sidewall forming at least one circumferential rib on the outer surface thereof and spaced a substantial distance below the top edge of said sidewall, and said lid being removably afiixed to the upper end of said sidewall via a resilient peripheral skirt extending downwardly past the lower edge of said rib on the container sidewall with the inner surface of said skirt having a portion complementary to said rib so as to mesh therewith, the lower portion of said skirt and said rib being adapted to cooperate with each other to deflect said skirt away from said rib as said lid is advanced downwardly over said sidewall until said complementary portion of said skirt is aligned with said rib whereupon said skirt returns to its normal position in meshing engagement with said rib.

18. A plastic container comprising the combination of a container of unitary construction and formed of selfsupporting plastic material, said container having a bottom wall and an integral sidewall extending upwardly therefrom, said sidewall forming at least one circumferential rib on the outer surface thereof adjacent the upper end thereof, and a lid of unitary construction and formed of self-supporting plastic material, said lid having a central portion which is reinforced to provide flexural rigidity in the direction of the longitudinal axis of said container, said lid being removably affixed to the upper end of said sidewall via a resilient peripheral skirt extend ing downwardly past the lower edge of said rib on the container sidewall with the inner surface of said skirt having a portion complementary to said rib so as to mesh therewith, the lower portion of said skirt and said rib being adapted to cooperate with each other to deflect said skirt away from said rib as said lid is advanced downwardly over said sidewall until said complementary portion of said skirt is aligned with said rib whereupon said skirt returns to its normal position in meshing engagement with said rib.

References Cited UNITED STATES PATENTS 2,695,115 11/1954 Roop 220-97 XR 3,189,072 6/1965 Starr 22039 XR 3,378,177 4/1968 Gran 220- XR FOREIGN PATENTS 56,473 5/1967 Germany.

GEORGE T. HALL, Primary Examiner US. Cl. X.R. 

